The developmental stages in the life cycle of Hyalomma asiaticum kozlovi were investigated under laboratory conditions. The larval, nymphal and adult ticks were all fed on rabbits at 25-27 degrees C, 50% relative humidity (RH) and exposed to daylight. All free-living stages were maintained in an incubator at 26+/-1 degrees C, 70% RH and daylight conditions. The life cycle of H. asiaticum kozlovi was completed in an average period of 151.6 days (range 104-190). The average developmental periods were 38.8 days for egg incubation, 2.1, 5.8 and 10.7 days for larval prefeeding, feeding and premoulting, and 3.3, 6.0 and 26.0 days for the same stages of nymphs, respectively. The average times for prefeeding, feeding, preoviposition and oviposition of female adult ticks were 1.4, 10.1, 20.9, and 26.5 days, respectively. The results confirmed the significant correlation between the weight of the engorged female and the amount of the egg mass laid (r=0.9641, p<0.05). The reproductive efficiency index (REI) and reproductive fitness index (RFI) in females were 8.82 and 7.56, respectively. Engorged nymphs moulting to females were significantly heavier (33.3+/-0.65 mg) than those moulting to males (27.1+/-0.79 mg). The overall sex ratio of the adult ticks was 1:1.07 (M:F).